Peptide cotransmitter at a neuromuscular junction

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Science  15 Jul 1983:
Vol. 221, Issue 4607, pp. 286-289
DOI: 10.1126/science.6134339


The neuropeptide proctolin (H-Arg-Tyr-Leu-Pro-Thr-OH) is present in the nerve terminals of an identified slow skeletal motoneuron in the cockroach. Proctolin is released onto the target muscle, a coxal depressor, by neuron stimulation and by depolarization with potassium. The physiological action of the motoneuron suggests that proctolin acts as a cotransmitter. Proctolin and neural stimulation produce delayed and sustained contractile effects without muscle depolarization.

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